encodings: add . and .. to all backends, except Drive

docs/content/overview.md

@@ -189,6 +189,14 @@ which will be specified in the documentation for each backend.
 | /         | 0x2F  | ／           |
 | DEL       | 0x7F  | ␡           |
 
+The default encoding will also encode these file names as they are
+problematic with many cloud storage systems.
+
+| File name | Replacement |
+| --------- |:-----------:|
+| .         | ．          |
+| ..        | ．．         |
+
 #### Invalid UTF-8 bytes {#invalid-utf8}
 
 Some backends only support a sequence of well formed UTF-8 bytes

fs/encodings/encodings.go

@@ -12,7 +12,8 @@ import (
 // Base only encodes the zero byte and slash
 const Base = encoder.MultiEncoder(
 	encoder.EncodeZero |
-		encoder.EncodeSlash)
+		encoder.EncodeSlash |
+		encoder.EncodeDot)
 
 // Display is the internal encoding for logging and output
 const Display = encoder.Standard
@@ -83,7 +84,7 @@ const Box = encoder.MultiEncoder(
 
 // Drive is the encoding used by the drive backend
 //
-// Encode invalid UTF-8 bytes as json doesn't handle them.
+// Encode invalid UTF-8 bytes as json doesn't handle them properly.
 // Don't encode / as it's a valid name character in drive.
 const Drive = encoder.MultiEncoder(
 	encoder.EncodeInvalidUtf8)